This invention relates to a projectile for electric rail guns and is of the type which has at its tail end an armature which serves as a current bridge between the current carrying rails of the gun.
Projectiles which are fired from rail guns are conventionally provided with an armature which serves as a current bridge between the gun rails. It is a desideratum that the armature establish a metal contact between the rails with the lowest possible electric resistance. Such armatures operate satisfactorily often only up to projectile velocities of a few hundred meters per second. At higher velocities, arcing between the armature and the rails occurs which causes a significant erosion of the contact faces of the armature thus leading to unnecessary energy losses and to a reduction of efficiency. The appearance of arcs is caused by the metal abrasion caused by the high contact currents. The removed metal particles leave gaps between the armature and the current-carrying rails and thus cause deterioration of the electric contact. Further, conventional metal contact armatures have a relatively high mass which has to be accelerated together with the mass of the projectile.
In order to avoid arcing, conventionally the projectiles have been often provided at their tail end with a metal foil which, at the initial passage of current, explosively vaporizes and forms a plasma. Such a "plasma armature" while functioning satisfactorily even at the highest projectile velocities has a high electric resistance and thus significantly reduces the efficiency of the rail accelerator.